The research described in this application is directed toward the establishment of artificial breeding in chimpanzees as a routine method of enhancing the size and quality of chimpanzee population available to the research community, and to elucidation of reasons for the apparent subfertility of a portion of the captive female population. Specifically, we shall undertake the insemination of a number of breeding females with semen from males who physiologically appear normal but whose incompetent reproductive bahavior has thus far excluded them from the genetic pool of the colony. We will use laparoscopy and radioimmunoassay of steroid and gonadotropic hormones to investigate the periovulatory events in females who have apparently normal menstrual cycles, but no history of successful pregnancy. Multiple inseminations will also be performed in these females. We also will carry out further experiments using rectal probe electrostimulation to refine our understanding of the mechanism by which this technique effectively initiates ejaculation and/or seminal emission. The results of this research will provide valuable information for the development of self-sufficient breeding colonies of great apes, and will provide information about a poorly understood area of infertility that will have application both to apes and man.